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docs: Clarify CLUTTER_ACTOR_IS_MAPPED

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There are a couple of gotchas in the 'mapped' flag that are not properly
documented, or are documented only in the actor_invariants.txt file; we
should have a proper description in the API reference as well, to avoid
confusion.
This commit is contained in:
Emmanuele Bassi 2011-10-25 11:30:46 +01:00
parent 8c196c9403
commit 81a82867e1
1 changed files with 16 additions and 7 deletions
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23
clutter/clutter-actor.c
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@ -222,13 +222,22 @@
*
* Evaluates to %TRUE if the %CLUTTER_ACTOR_MAPPED flag is set.
*
* Means "the actor will be painted if the stage is mapped."
* The mapped state is set when the actor is visible and all its parents up
* to a top-level (e.g. a #ClutterStage) are visible, realized, and mapped.
*
* %TRUE if the actor is visible; and all parents with possible exception
* of the stage are visible; and an ancestor of the actor is a toplevel.
* This check can be used to see if an actor is going to be painted, as only
* actors with the %CLUTTER_ACTOR_MAPPED flag set are going to be painted.
*
* Clutter auto-maintains the mapped flag whenever actors are
* reparented or shown/hidden.
* The %CLUTTER_ACTOR_MAPPED flag is managed by Clutter itself, and it should
* not be checked directly; instead, the recommended usage is to connect a
* handler on the #GObject::notify signal for the #ClutterActor:mapped
* property of #ClutterActor, and check the presence of
* the %CLUTTER_ACTOR_MAPPED flag on state changes.
*
* It is also important to note that Clutter may delay the changes of
* the %CLUTTER_ACTOR_MAPPED flag on top-levels due to backend-specific
* limitations, or during the reparenting of an actor, to optimize
* unnecessary (and potentially expensive) state changes.
*
* Since: 0.2
*/
@ -243,7 +252,7 @@
* actor wants to delay allocating resources until it is attached to a
* stage, it may use the realize state to do so. However it is
* perfectly acceptable for an actor to allocate Cogl resources before
* being realized because there is only one GL context used by Clutter
* being realized because there is only one drawing context used by Clutter
* so any resources will work on any stage. If an actor is mapped it
* must also be realized, but an actor can be realized and unmapped
* (this is so hiding an actor temporarily doesn't do an expensive
@ -264,7 +273,7 @@
*
* Note that an actor is only painted onscreen if it's mapped, which
* means it's visible, and all its parents are visible, and one of the
* parents is a toplevel stage.
* parents is a toplevel stage; see also %CLUTTER_ACTOR_IS_MAPPED.
*
* Since: 0.2
*/